Nelson Mandela at Robben Island Prison

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South African political activist and leader Nelson Mandela, left, in the prison yard of the Robben Island Prison with fellow prisoner and African National Congress member Walter Sisulu. Mandela was charged with sabotage and sentenced for life in the maximum security prison off the coast of South Africa, near Cape Town, during the infamous 1964 Rivonia Trial. He was eventually released in 1990.

South African political activist and leader Nelson Mandela, left, in the prison yard of the Robben Island Prison with fellow prisoner and African National Congress member Walter Sisulu. Mandela was charged with sabotage and sentenced for life in the maximum security prison off the coast of South Africa, near Cape Town, during the infamous 1964 Rivonia Trial. He was eventually released in 1990. (Getty Images)

South African political activist and leader Nelson Mandela, left, in the prison yard of the Robben Island Prison with fellow prisoner and African National Congress member Walter Sisulu. Mandela was charged with sabotage and sentenced for life in the maximum security prison off the coast of South Africa, near Cape Town, during the infamous 1964 Rivonia Trial. He was eventually released in 1990.